There are two established rules for withdrawing American troops from foreign conflicts. The first is: Don’t do it now. The second is: Don’t do it later.

President Donald Trump’s reasoning and strategy in demanding a pullout of our forces from Syria suffer from his usual decision-making flaw, lacking both reasoning and strategy. The timing is also questionable. He says now is the right time because the Islamic State has been defeated, a judgment that is premature at best. And he disregarded the advice of Defense Secretary James Mattis, who promptly resigned.

But if Trump is too eager to get out, his critics are too committed to staying. The direct U.S. intervention began in 2014, when Barack Obama ordered a campaign of airstrikes against Islamic State targets in Syria. Special operations forces were deployed to Syria in 2015. Trump expanded our ground troops to about 2,000.

Once we put boots on the ground, the default option is to keep them there. If the fight is going badly, we need them to avert defeat. If the fight is going well, we need them to keep the enemy down. If there’s a stalemate, we need them to preserve it. If the fight ends in victory ... well, we don’t have a contingency for that, because no one imagines it happening.

The foreign policy hawks are unhappy because they treat intervention as a one-way tunnel with no exits. Earlier this month, Joint Chiefs Chairman Joseph Dunford said we’ve trained only 20 percent of the local forces that are needed. “We still have a long way to go, and so I'd be reluctant to give a fixed time,” he said.

Brett McGurk, who was special presidential envoy for the global coalition to defeat ISIS until he resigned Saturday, had previously seemed to think he had a lifetime job. “Defeating a physical caliphate is one phase of a much longer-term campaign,” he said Dec. 11. “This will really take a period of years.”

Where have we heard that before? Aside from a short break, we’ve been in Iraq since 2003. Before long, we’ll have men and women serving in Afghanistan who weren’t born when we invaded Afghanistan.

Until recently, Trump administration officials were trying to lock us into a commitment in Syria that went beyond defeating the Islamic State. “We’re not going to leave as long as Iranian troops are outside Iranian borders, and that includes Iranian proxies and militias,” national security adviser John Bolton vowed, adding, “That means we are not in a hurry.”

No kidding. To get an idea of how long he might have in mind, consider that Iran has been supporting its proxy organization Hezbollah, which operates mainly in Syria and Lebanon, for more than 30 years. Bolton’s pledge was to make this another front in a modern Hundred Years’ War.

Neither Obama nor Trump ever tried to mobilize public support for a venture that was unclear in purpose, open-ended and peripheral to our national security. If Syria were as vital as many people in Congress insist, they could have authorized the president to wage war there. Instead, members on both sides of the aisle did their best impersonation of potted plants.

Now that the president wants to take our troops out of harm’s way, a chorus of critics want to direct U.S. policy. Sen. Lindsey Graham, R.-S.C., said the pullout is “akin to surrendering.” Sen. Marco Rubio, R-Fla., called it “a terrible decision.” Even some Democrats agree.

The problem is that every U.S. military intervention leads us into another, with dismal results. The invasion of Iraq to topple Saddam Hussein was supposed to be a brief project, but the chaos we unleashed forced us to stay on. Our occupation generated an insurgency, and our effort to crush it helped spawn the Islamic State.

The group expanded into Syria, inducing us to fight there. If the hawks had their way, we would remain indefinitely. In the process, we would probably create new enemies who would also have to be fought.

Trump’s impulsive nature suggests that this policy, like most of his, will be executed as poorly as humanly possible. It’s always easier to get into a war than to get out. It’s entirely possible that withdrawing will make things worse in the near term. But the idea that the old policy would yield a successful conclusion — or any conclusion — had no basis in reality.

If the choice were between leaving Syria right away and leaving in six months or a year, taking our time might be defensible. More likely, though, it’s now or never.